1. Field
The present disclosure relates to impact-modified polycarbonate compositions that comprise a first graft polymer comprising silicone-acrylate composite rubber as a graft base, wherein the amount of silicone rubber is from 65 to 95 wt. % (based on the graft base), and a second graft polymer containing free copolymer, that is to say copolymer that is not chemically bonded to the rubber, and having a weight-average molecular weight of from 60,000 to 150,000 g/mol. The use of the polycarbonate compositions in the production of moulded articles, and to the moulded articles themselves is also disclosed.
2. Description of Related Art
US 2002/077417 A1 discloses flame-protected compositions comprising (a) polycarbonate, (b) graft polymer with a silicone-acrylate composite rubber, wherein the ratio of silicone to acrylate is from 99:1 to 1:99, (c) optionally filler, for example talc, (d) phosphoric acid esters as flameproofing agents, (e) optionally further additives, for example ABS, SAN and antidripping agents. There are disclosed as examples compositions comprising Metablen® S-2001, which is a graft polymer with a graft base of silicone-butyl acrylate composite rubber, which consists of about 17 wt. % methyl methacrylate, about 9 wt. % organosiloxane and about 74 wt. % butyl acrylate. However, US 2002/077417 A1 does not disclose compositions comprising a graft polymer with a silicone-acrylate composite rubber as graft base, wherein the amount of silicone rubber is from 65 to 95 wt. % (based on the graft base).
JP-A 08-259791 discloses flame-protected compositions comprising polycarbonate and a silicone-acrylate rubber with from 30 to 99% siloxane.
JP-A 2000-017136 discloses compositions comprising polycarbonate, from 1 to 40 wt. % oligomeric phosphoric acid esters and graft polymer with a graft base of silicone-acrylate rubber which contains from 60 to 99 wt. % polyorganosiloxane, optionally polytetrafluoroethylene and optionally talc.
JP-A 2002-069282 discloses compositions comprising polycarbonate, composite rubber (for example Metablen® SX-005), oligomeric phosphoric acid esters, silicone oil, optionally polytetrafluoroethylene and optionally additives.
WO-A 00/39210 discloses compositions comprising polycarbonate, copolymer, oligomeric phosphoric acid esters, graft polymer (for example Metablen S-2001) with a silicone-acrylate rubber as graft base, wherein the amount of polyorganosiloxane is from 3 wt. % to 90 wt. %, optionally polytetrafluoroethylene and a reinforcing material, for example talc.
EP-A 0 641 827 discloses compositions comprising aromatic polycarbonate, graft polymer of vinyl monomer on diene rubber, phosphoric acid esters, polytetrafluoroethylene, inorganic filler, for example talc, and composite rubber of silicone and acrylate rubber.
JP-A 07316409 discloses compositions comprising polycarbonate, phosphoric acid esters, graft polymer with a silicone-acrylate rubber as graft base, wherein the amount of polyorganosiloxane is from 1 to 99 wt. % and the amount of polyalkyl (meth)acrylate rubber is from 99 to 1 wt. %.